The present invention relates to electro-optically induced waveguides.
Modern fiber optic networks for applications such as optical telecommunication or remote optical sensing include in their architecture a wide variety of different devices, which provide functionalities such as routing, modulating, splitting or intensity attenuation of transmitted optical signals. The so-called electro-optically induced waveguides, in short EOIW, also known as field-induced or voltage-induced waveguide, may serve as key elements in the design of such devices.
The change in the optical properties, i.e. refractive index n(E) of a material, in the presence of an external electrical field describes the electro-optic effect, which is given by the following relation:
                              n          ⁡                      (            E            )                          =                              n            0                    +                                    1              2                        ⁢                          n              0              3                        ⁢            rE                    +                                    1              2                        ⁢                          n              0              3                        ⁢                          sE              2                                +          …                                    (        1        )            
The linear term in E is referred to as the Pockels effect, with r being the Pockels constant, while the quadratic term in E describes the electro-optic Kerr effect with s being the electro-optic Kerr constant. The Pockels effect occurs and is large in non-centrosymmetrical crystalline media, while the electro-optical Kerr effect is large in certain liquids and ferroelectric ceramics. These materials are called here Pockels materials and electro-optic Kerr materials, respectively.
An electro-optically induced waveguide may consist of a core layer made of a material of large electro-optic constants, which is placed in between two cladding layers of equal or smaller refractive index than the core, as well as in the proximity of an electrode arrangement. The principle of an electro-optically induced waveguides is described for example in [1]. An electrical field applied between the electrodes of the electrode arrangement and across the waveguide layer stack causes a local change in the refractive index of the core material, and, as a result, an optical waveguide is induced. The waveguide can be turned “on” and “off” respectively by means of manipulating the electrical field strength. Scientific publications [2, 3], patents and patent applications [4-8] propose two main designs for the electrode configuration of an electro-optically induced waveguides: an ‘in-plane’ configuration [4], [6-8], an example is given in FIG. 1A, and an (‘out-of-plane’ configuration [5, 8], an example is given in FIG. 1B.
Electro-optically induced waveguides may be used for switching, modulation, power splitting, and variable optical attenuating of optical signals transmitted between optical fibers in fiber optic networks. Moreover photonic applications, known by the skilled person, which employ miniaturized optical benches where free space propagation of light is needed, for instance to reduce optical beam divergence etc., can also benefit from devices based on such waveguides.
The problem to be solved is to reduce complexity and costs of a network having at least one electro-optical device with at least one electro-optically induced waveguide.